For the researcher who supervised this first emergency study, the glass is half full. Preliminary results published on Tuesday (zip archive here) suggest that if the Omicron variant is much more resistant to neutralizing antibodies than the original strain of sars-CoV-2 or the Delta variant, it does not completely escape the action of Pfizer’s vaccine. This means that the messenger RNA vaccines, with three doses, should still offer effective protection to prevent deaths and the most serious effects of Covid-19.
First live neutralization assay for Omicron. 2 doses of Comirnaty not enough for neutralization in most cases. Infection (with D614G, ie the original virus) plus 2 doses of Comirnaty was enough for neutralization.https://t.co/RyKm73gobk https://t.co/Be4CCKC7KJ
– Mike Dee (@MikeDeeeeeee) December 7, 2021
The study was conducted by teams from Alex Sigal at the Africa Health Research Institute in Durban. It is the first to examine the behavior of the Omicron variant in vaccinated people. Be careful, it only relates to neutralizing antibodies, which are only part of the immune response, and on a sample of only 12 patients. The preliminary results have not yet been evaluated by the scientific community but have nevertheless been published because they are in the general interest.
Significant drop in neutralization in double vaccinated
In the six patients who had received two doses of Pfizer’s vaccine but had never been infected with Covid-19, antibody neutralization drops sharply, by a factor of 41 – compared to the original strain. But the silver lining is that the five patients previously infected with Covid-19 “benefit from a relatively high neutralization against Omicron”. It is for this reason that researchers believe that people who have received three doses of the vaccine should enjoy relatively similar protection to this group. Indeed, a third dose boosts the level of neutralizing antibodies by a factor of at least 35.
“It’s better than I expected,” writes Alex Sigal on Twitter. “The fact (that Omicron) still needs ACE2 receptors (to attach itself to a cell) and that it only partially escapes (the vaccine) means that this is a problem that can be tackled with” the tools we have. “
The relatively optimistic WHO
“There is no reason to doubt” that current vaccines protect patients infected with Omicron against severe forms of Covid-19, Michael Ryan, the WHO emergency manager, said on Tuesday in a report. interview with AFP.
“We have very effective vaccines that have been shown to be potent against all of the variants so far, in terms of disease severity and hospitalization, and there is no reason to believe that would not be the case. “With Omicron, explained Dr. Ryan, while stressing that we were at the very beginning of the studies of a variant detected only on November 24 and which has since been spotted in about forty countries.
“Encouraging” signals, according to Dr Fauci
According to Michael Ryan, there are also no indications, at this point, that Omicron is causing more severe forms of Covid-19. His words echo to those of Dr Anthony Fauci, White House adviser on the health crisis. “Clearly, in South Africa, Omicron is transmitted more “, begins Dr Anthony Fauci, White House adviser on the health crisis, in an interview with CNN this Sunday, referring to the “vertical” curve in the number of new cases in this country. “But so far, even though it’s too early to draw any firm conclusions, it doesn’t look like it has a high degree of seriousness,” he said. “So far, the signs regarding gravity are a little encouraging,” he repeated.
In the field, several South African hospitals have indicated that many patients positive for the Omicron variant did not appear to have more serious symptoms. But in a very young country, with a median age of 26.4 years, it is not excluded that serious cases will emerge in the coming weeks.